Method of and apparatus for recording signals electrically



R..L VVHSE June 25, 1940.

METHOD OF AND APPARATUS FOR RECORDING SIGNALS ELECTRICALLY 4Sheets-Sheet 1 Filed June 29, 1938 FIG.\

INVENTOR R J VVISE MOEN'MF June 25, 1940. 155 2,205,450

IETHOD OF AND APPARATUS FOR RECORDING SIGNALS ELECTRICALLY Filed June29, 1938 4 Sheets-Sheet 2 INVENTOR R. J WISE BY J ATTORNE R. J. WISE-June 25, 1940.

uzwacn OF AND APPARATUS FOR asconnma SIGNALS ELECTRICALLY Filed June 29.1938 4 Sheets-Sheet 3 FIG. 4

June 25, 1940. J 155 2,205,450

METHOD OFIAND APPARATUS FOR RECORDING SIGNALS ELECTRICALLY Filed June29, 1938 4 Sheets-Sheet 4 PIC-3.6

FIG.7

INVENTOR I04, R. J. W'ISE l atented June 25, 1940 PATENT OFFICE METHODor AND APPARATUS FOR REQORD- IN G SIGNALS ELECTRICALLY RaleighJ. Wise,Dunellen, N. J., assignor to The Western Union Telegraph Company, NewYork, N. Y., a corporation of New York Application June 29, 1938, SerialNo. 216,455

18 Claims.

The present invention relates to the reception of pictures and othersubject matter and more particularly to novel means for reproducing afacsimile of a transmitted picture or drawing. In accordance with theinvention a pattern of marking material representing receivedsignals isdeposited upon a transfer member and thereafter this pattern istransferred to the record sheet. Accordingly the primary object of thepresent invention is to provide a facsimile receiver embodying means formarking a message sheet by atransfer method.

Another object of the present invention is to provide a novelpaper-feeding means on,a facsimile machine employing a transfer memberof the helical type.

Still another object of the present invention is to obtain apatternrepresenting a scanned line of a picture or message for ultimatetransfer to a record surface.

Other and more specific objects of the invention are defined by theterms of the appended claims and will be apparent from the followingdescription taken in connection with accompanying drawings in which:

Fig. 1 is a fragmentary view in perspective of a facsimile recorderillustrating in detail features in which the invention resides;

Fig. 2 is a fragmentary view in side elevation of a modification;

Fig. 3 is a sectional view in front elevation on line 3-3 of Fig. 2;

Fig. 4 is a fragmentary view in front elevation of another modification;

Fig. 5 is a view in side elevation of the apparatus illustrated by Fig.4;

Fig. 6 is a top plan view of still another modification of theinvention; and

Fig. 7 is a section on line 1-1 of Fig. 6 as viewed in the direction ofthe arrows.

Referring now more particularly to Fig. 1, the apparatus comprises adrum ill or transfer wheel secured onashaft l I whichis supported forrotation by suitable bearings (not shown) andwhichcarries a toothedpulley I2 positively driven by a perforated belt or chain l3 from atoothed pulley or sprocket I4 mounted on the armature shaft of thedriving motor 15. The cylinder I0 is provided with a helical rib I8which contacts the record sheet or web 19 along the edge 2| where theweb passes over the bail member or printer bar 22. The web I9 is drawnfrom a rotatably mounted supply reel 23 preferably at a constant rate ofspeed by means of a power driven friction roller 25 cooperating with thefriction rollers 26. I The rollers 26 are carried by a shaft or rod 21which is pressed downwardly by a spring means not shown so that thepaper is firmly held between the roll 25 and the rollers 26. Rotarymotion is imparted to the shaft 28 of 5 the roller 25 from the shaft IIby means of a perforated belt or chain 29 in cooperation with pulleys orsprockets 3| and 32. Toinsure that the roller 25 will operate in stepwith the cylinder ill, the belt 29 may be perforated as shown 10 forengagement with the sprocket teeth 33 on both of the pulleys.

The position of the bail 22 with respect to the portion of the web l9which extends from the bail to the feed rollers 25 and 25 is animportant fea- 15 ture of the present invention. The bail 22 is providedwith radial arms 35 which are swingably mounted upon a stationary rod orshaft 31. The latter is located so that it is tangent to the upper partof the paper web l9 when the edge of 20 the bail 22 is in contact withthe helical transfer member IS. A pair of springs 38 engaged at theirfree ends beneath the arms 35 press the bail 22 upwardly so that itsedge 2| presses the sharply folded web firmly against the helical 26member l8. With the arrangement just described, the pressure of the bailagainst the helical member I8 is virtually independent of the paper feedtension. This insures substantially constant contact of the record sheetI9 80 with the helical member l8. This feature of the invention may beused in recorders employing electrically sensitive papers in contactwith a helical recording drum.

A printer bar 39, having a relatively sharp 35 edge 40, is mounted uponthe upper end of a pair of rods 42 and 43, the latter each beingconnected in a suitable manner to the signal responsive members of apair of conventional loud speaker units 44 of suitable design. The loudspeaker units 44 are illustrated as being of the permanent magnet type,but it is to be understood that they may have separately excited fieldcoils or that any suitable type of motor unit or units may be employedto operate the printer 45 bar 40. The movement of the swingable barmembers 42 and 43 is limited by adjustable stop members 46 and 41 in theform of set screws engaged in a stationary part of the machine (notshown) and locked in the desired position by 0 means of lock nuts 48.

In the arrangement shown which forms no part of the present invention,incoming signals are fed to the motor units of the recorder from theline L by way of the transformer 50 and the amplifier II. The amplifierII is connected by way of the transformer 52 to a rectifier comprising apair of vacuum tubes 88, the anodes of which are connected the motorunits 44 and the anode supply battery 86'.

A typewriter ribbon 66 serves as a source of marking material which isintimately transferred, under control of signals from the line L, to therecord sheet I8 by the helical member I8. The typewriter ribbon 56 iscarried in a conventional manner by a pair of spools 61 and 58 and isheld in position before the printer bar 38 by means of a. pair ofvertically spaced channelshaped members 6|, the latter being fixed ateach end in stationary members 62 each positioned adjacent the ends ofthe cylinder I0.

In order to provide a constant supply of fresh ribbon, either of thereels 61 and 68 may be driven from pinions 68 and 64 secured on thespool shafts 85 and 66 respectively which mesh selectively with pinions61 and 68 secured for rotation on the axially movable shaft 68. Theshaft 68 is slidably mounted adjacent each end in stationary bearingmembers I0 and is driven from the motor pinion II, which is in mesh witha gear I2 secured to the pinion shaft. Means (not shown) is preferablyprovided for moving the shaft 68 axially when the ribbon 56 iscompletely wound on either of the spools 51 or 58. A pad I3, which ispressed upwardly against the helical member I8 as by springs I4, one ofwhich appears in the drawings, is provided to wipe off the coloringmaterial remaining as the member I8 transfers the pattern thereon to theweb I8 and before it receives a new portion of the pattern for the nextscanning line.

During operation of the picture recording apparatus just described, theinterconnected motor units 44 are supplied with electrical currents fromthe amplifier 62 and the rectifier 88 controlled in accordance withsignals received over the line L. When this current reaches a certainpredetermined value, the signal actuated member in this case theprinting bar 40, is moved inwardly, thus pressing the ribbon. 86 againstthe helical ridge II which results in the depositing of a quantity ofthe pigment thereon from the ribbon 66. If the printing member 40 wereheld in contact with the helical member I0 during one completerevolution of the drum I0, a solid black line extending across the webI8 at its fold would be produced. The actual number of marks and theirlengths produced in each scanning line is therefore determined by thenumber of times and the duration of each that the printing member 40presses the ribbon 56 against the member I8 during each revolution ofthe scanning drum I0. It

will be apparent to those skilled in the art that any suitable means maybe utilized for producing synchronism. between the moving parts of theapparatus by which the picture is transmitted and the moving parts ofthe recording apparatus described above.

A modified form of recorder is shown in Figs. 2 and 3 of the drawingswhich embodies the transfer feature of this invention. Referencecharacter 15 designates a cylindrical copy holder which is mounted upona shaft 76, the latter being supported and driven, for example, in themanner disclosed in applicant's copending application, Ser. No. 84,935,filed June 12, 1936. A message blank Il wrapped around the copy holderI5 is secured thereon by any suitable means. The transfer means of thismodification comprises the relatively sharp edge it of a signal transferwheel 18 secured to a shaft 80 which is journaled for rotation in a pairof upright members 8|. The last named members are joined adjacent theirlower ends by a rod 82 which is journalled in a pair of ears 83extending upwardly from a platform member or base 84. The uprightmembers M are biased toward the copy holder 16 by springs 85 connectedto upstanding legs of a U-shaped bracket 86 secured to the base byfastening means 81. A pad 88 of ab sorbent material such as felt iscarried by the bracket 86 and is pressed against sharp edged peripheryI8 of the signal transfer wheel so as to cleanse it and prepare it forthe reception of a fresh supply of pigment or any suitable markingmaterial. An ink reservoir 88 is mounted between the arms 8I and isprovided with one or more contacting inking rollers 8I and 82, theformer of which dips intov a body of marking fluid such as ink containedin the reservoir 88 so as to transfer ink from. the roller 82 to thesharp edged periphery I8 of the signal transfer wheel I8.

An electromagnetic recorder unit 83 which may, if desired, be similar toone of the motor units 44 previously described, is provided with anarmature 84, the upturned free end 85 of which is adapted to engage thesharp edge I8 of the signal transfer wheel. The free end 88 of thearmature is preferably very thin and is notched as shown at 86 to insuregood pigment scraping contact with the sharp edge I8 of the transferwheel. The leads 81 extending from the electromagnetic recorder unit areconnected so as to receive signals from. the line L in the manneralready and fully described. in connection with Fig. 1 of the drawings,

The platform 84 is carried by a pair of guidesor rods 88 and 88 uponwhich it slides on bear ing shoes MI and I02. The bearing member IOIembraces the rod 88 so that the platform 84 may be tilted upwardly, thuspermitting a halfnut I03 which is secured to the base to be disengagedfrom the propelling lead screw I04. The halfnut I08 is carried on aresilient arm I06 secured at I01 to the platform 84. A stop member I08may be provided on the bracket 86 to lift the transfer wheel '18 out ofcontact with the blank II when the halfnut is disengaged from the leadscrew thus permitting the entire carriage comprising the base 84 to bemoved along the blank I1.

In operation of the modified form of apparatus of Figs. 2 and 3, amessage blank TI is secured in any manner around the periphery of thecylinder I5 and the platform 84 which carries the scanning apparatus ispositioned with the transfer'wheel I8 in contact with the blank adjacentone edge thereof. Rotation is imparted to the cylinder I5 and the signaltransfer wheel is rotated by reason of its frictional contact with theblank II, the lead screw I04 advancing the signal transfer wheel axiallyof the drum I5 to provide a scanning action.

Coloring matter is applied to the sharp edged periphery 18 of thetransfer wheel from the rollers 9| and 82 and if the armature 84 isnormally biased away from the blank, in the absence of line signals, acontinuous helical line will be traced around the blank II which willresultin the blank 11 being covered uniformly with the pattern of lines.However, if the armature is normally biased into contact with the blank,in the absence of line signals, no mark will be produced on the blank11. Positive or '5 of the drawings.

negative signals may be used for transmission depending on the normalbias of the armature in a manner now to be described.

Assuming that facsimile signals representing a negative copy of thetransmitted subject-matter are being supplied from the line L to thedevice 93 having an armature biased to remain out of contact with thewheel during absence of signals, portions of the ink will be removedfrom the edge 18 of the transfer wheel when the armature moves upwardly.The remaining portions of the marking material will be left on theperiphery I8 of the wheel 19 for transfer to the blank 11. In thismanner a positive facsimile copy of the transmission subject matter willbe reproduced.

If the transmitted signals represent a positive of the transmitted copy,the armature of the motor device 93 can be biased normally into contactwith the blank so that a positive copy will be reproduced.

Another modification embodying the transfer feature of the invention isshown in Figs. 4 and Referring now to these figures reference characterIII designates a cylindrical copy holder similar to the copy holder 15of Figs. 2 and 3 which is rotated by means (not shown) known to theprior art. The cylinder III is provided with a recording blank 'I'Iasecured thereon in any suitable manner so that the signal transfer wheelII2 will roll against it when the cylinder III is rotated. The wheel H2is mounted by a spindle II4 journalled in frame members II5, like framemembers 8| of Fig. 3, which are joined together adjacent their lowerends by a member H6. The last named member is pivoted in the brackets II1 secured to the platform or base IIB. This platform is mounted upon apair of guide members 98a and 99a in the manner already described inconnection with Fig. 2 of the drawings. A half nut III3a carried by amember Ililia which is secured to the platform H8 at IDIa engages a leadscrew "1411 so as to propel the wheel II2 longitudinally of the cylinderIII to produce a scanning action.

The wheel I I2 has a sharp edged periphery I2I which is continuouslysupplied with ink from an inking roller 920 which is in contact with apartially or wholly immersed roller 9Ia. The spindles of these rollersare journalled in the wall of the ink reservoir 89a in the mannerdescribed in connection with Fig. 3.. A conduit I22 in communicationwith a convenient source of air or other fluid under pressure isprovided with a nozzle I 23 having a very fine opening which projectsair in a stream upon the peripheral edge I2I of the wheel II2. This airstream when it impinges on the wheel II2 removes ink therefrom so thatno mark is transferred to the blank 'I'Ia. To provide control of the airstream in accordance with line sigupon receipt of signals over the lineL.

nals and thereby to cause the ink rema ning on or, if desired, removedfrom the wheel II2 to represent line signals, an electromagneticallycontrolled valve member I24 ending in the form of a vane I25 ispositioned to cover at times the nozzle I23. A signal controlled motordevice I21, which may be a loud speaker unit of the type previouslydescribed, is operatively connected to the valve member I24 to withdrawthe vane I26 from the opening of the nozzle I23 It Will be understoodthat actuation of the vane may depend on an absence of line signals inwhich case a positive copy will be produced from signals representing anegative. A type of motor unit having an adjusting device indicated atI29 is preferably selected so that the normal or inoperative position ofthe vane I26 may be set prior to the beginning of a recording operation.

In operation of the modified recorder just described, ink is supplied tothe reservoir 89a and the cylinder III is caused to rotate insynchronism with a more or less remote transmitter. With no signalsbeing supplied from the line L to the motor unit I21 by way of its leads91a, the vane I26 is moved to cover the nozzle I23 by the adjustingmeans I29 until no mark appears on the record sheet'IIa. This is thecorrect adjustment for best operation of the recorder and it will benoted that this adjustment may also be obtained when a signal issupplied to the motor unit I21 in the event that picture reversal is tobe had withsignals being received by the motor means I21 as explainedabove. The vane I26 will be vibrated longitudinally in accordance withthe signals which represent the transmitted subject matter and inkremaining on the periphery of the wheel II2 will be transferred to themessage blank 11a in the manner already described in connection withFig. 2 of the drawings.

A modification somewhat similar in detail to the embodiment disclosed inFigs. 2 and 3 of the drawings is illustrated in Figs. 6 and 7. In thelast named figures of the drawings reference character 15a designates acylindrical copy holder mounted upon the shaft 16a which is supportedand driven in the manner already described in connection with Figs. 2and 3. Power for driving the cylinder 15a and lead screw I04a is derivedfrom a motor I32 which is provided with a driving pinion I33 as shown inFig. 6 of the drawings. It will be understood that suitable gearing isprovided between the motor pinion I33 and the message drum and leadscrew in a manner well known to those skilled in the art. The transfermeans of this modification which cooperates with a message blank 'I'Iacomprises the relatively sharp edge 18a of the signal transfer wheel 19awhich is mounted upon a shaft a journaled in the uprights BI a.

by the upstanding apcrtured ears 83a. The pivoted support for thetransfer wheel 19a. which comprises the members 8Ia just described isadapted to be moved so as to withdraw the wheel 19a from contact withthe message blank by a solenoid I3I having a pull rod I36 pivotallyconnected at or adjacent its end to the cradle member. The point ofpivotal connection is indicated by the reference character I31. A padI38 of absorbent material such as felt or the like is carried by a shaftI39 journaled at its ends in a pair of similar frame members I4 I.

The means for supplying the pattern of marks to the periphery 18a of thetransfer wheel will now be described in detail. It comprises anelectromagnetic recorder unit I42 of any of the types similarlymentioned which is secured in a suitable manner to the frame members MI.The recording unit is provided with a vibrator armature member I43bifurcated as shown in the drawings, each arm I46 of the bifurcationbeing provided with an aperture I47. The marking material such as ink isapplied to a strand such as a thread of silk I49. The thread is woundupon two spools I 5| and I52, these latter being carried by shafts I53and I54 journaled in bear- The upright members 8Ia are -mounted on a rod82a which is pivotally received ing blocks I56 in order to permit thedirection of movement of the thread to be reversed when it is completelywound on either of the spools. The reel shafts may be driven frompinions III and I58 which mesh selectively with pinions I66 7 and I6Isecured for rotation on the axially movable shaft Ifl. The shaft I63 isslidably mounted adjacent each end in stationary members I and is drivenfrom the motor-pinion 133 which is in mesh with a gear I66 secured tothe pinion shaft I63. Means (not shown) is preferably provided formoving the shaft I63 axially when the thread I 49 is completely wound oneither of the reels.

Coloring material is supplied to the thread I49 from an inking pad orroller I61 dipping into an ink reservoir I66. This reservoir issupported from the base member 84a of the apparatus by a bracket I69.

In order to compensate for inclination of the thread I46 as it is woundin more or less quantity on either of the spools I5I and I62, guidemembers III are provided which are secured to the frame members Ma. Theguide members III are provided with eyelets I12 through which the threadis passed.

In operation of the apparatus of Figs. 6 and 7 just described andassuming that blank Ila is in place on the recording cylinder, pictureor message signals are supplied in a well known manner to the motor unitI42 by way of the leads IBI. The thread I49 as it leaves the reel I5! issupplied with a quantity of ink from'roller I61 which is applied to theperiphery 18a. of the transfer wheel when the armature I63 of therecorder unit moves to the left as viewed in Fig. 6 in response to asignal. It will be understood that the armature I43 vibrates inaccordance with the received signals and that therefore a pattern ofmarks will be applied to the periphery 16a of the transfer wheel fortransfer to the message blank I'Ia. In order to secure maximumeffectiveness with the apparatus an ink roller I61 similar to thatdescribed above is preferably mounted adjacent the spool I52.

In this form of the invention a separate inking roller in contact withthe periphery of the transfer wheel may be used in which case the threadwill remove ink from the periphery of the wheel in response to signalsin a manner similar to that described in connection with the armature 94of Figs. 2 and 3. From the foregoing it will be seen that this inventionprovides recorders which operate in accordance with novel principles andwhich are cheap to manufacture and can be used on ordinary paper or anyother material which presents a surface of any color capable ofreceiving ink.

While the invention has been described and explained in detail inconnection with four illustrative embodiments thereof, it is to beunderstood that the invention may be embodied in other forms and,therefore, the invention is not limited except as indicated by the termsand scope of the appended claims.

What is claimed is:

1. The combination of a scanner for the reception of facsimile signalsincluding transfer means and means to support a recording surface inengagement with said transfer means, means to cause said transfer meansto scan said recording surface and means to provide said transfer meanswith marking material in accordance with received facsimile signals fortransfer to said recording surface.

2. In a facsimile recorder, to hold a record sheet, a marking device andmeans to support the same for contact with said sheet,

means to cause said marking device to scan said record sheet and meansto provide said marking device with a pattern of marking material, saidpattern of marks representing line signals.

3. The combination of scanning means including a rotatable spiral memberand a cooperating printer member arranged to be moved substantiallyradially with respect to said spiral member, means interposed betweensaid printer member and said spiral member to apply marking material tothe latter upon. radial movement of the printer member, and meansarranged to support and move a record receiving sheet in continuouscontact with said spiral member at a point spaced circumferentially fromsaid printer member.

4. The combination of claim 3 wherein said means interposed between saidprinter member and said spiral member is a typewriter ribbon, means tosupport and guide said ribbon, and means for feeding and receiving saidribbon whereby it is moved longitudinally.

5. The combination of a scanner including a rotatable transfer memberand means to support a record receiving surface in contact with saidtransfer member, means to cause said transfer member to scan said recordreceiving surface and inking means to provide said transfer member withmarking material in accordance with signals for transfer to saidrecording surface.

6. In. a facsimile recorder, means to hold a record sheet, a markingwheel and means to support'the same in contact with said sheet, means tocause said marking wheel to scan said record sheet and means to providesaid marking wheel with a pattern of marking material, said pattern ofmarks representing line signals.

7. The combination of scanning means including a rotatable spiral memberand a cooperating printer member arranged to be moved radially spiralmember to apply marking material to the latter upon radial movement ofthe printer member, and means comprising a pivotally mounted bailarranged to support and move a record receiving sheet in continuouscontact with said member at a point spaced circumferentially from saidbar.

8. In a facsimile recorder, scanning means including a transfer member,means to apply marking material to said member in accordance withsignals, means to support. and move a record sheet comprisingcooperating feed rollers at least one of which is power driven, a bailmember and means to swingably mount said bail member for engagement withsaid transfer member, and guide means located substantially at the axisof movement of saidbail member to guide said record sheet whereby thecontact pressure of said bail member on said transfer member isunaffected by the tension applied to the sheet by said feed rollers.

9. A recorder comprising transfer means, electrically operated means toapply recording material to, said transfer means, means to apply tensionto a record sheet to advance the same, a. pressure member free to movein an arcuate path into contact with said transfer member, and a guidemember located substantially at the center of the arcuate movement ofsaid pressure member, said-record sheet being looped over said pressuremember and passing over said guide member, the location of said guidemember with respect to said pressure member acting to prevent thetension on said sheet from affecting the contact pressure of saidpressure member'on said transfer means.

10. The combination of scanning means including a rotatable spiralmember, and a cooperating bar arranged to be moved radially with respectto said member, means interposed between said bar and said member toapply marking material to the latter upon radial movement of the bar,means arranged to support and move a record receiving sheet incontinuous contact with said member at a point spaced circumferentiallyfrom said bar, and means to remove marking material remaining aftercontact with said sheet, from said member.

11. The combination of scanning means including a rotatable spiralmember, means intermittently to apply a marking medium to said memberincludinga cooperating bar arranged to be moved radially with respect tosaid member, and means arranged to support and move a record receivingsheet in continuous contact with said member at a point spacedcircumferentially from said bar.

12. The combination of a scanner including a transfer wheel and arotatable cylinder adapted to hold a record sheet in contact with theperiphery of said transfer wheel, means to apply marking material on theperiphery of said transfer wheel, means to remove portions of saidmaterial from said wheel, in accordance with signals so that only theremaining material will be transferred to said sheet continuously toform a facsimile record, and means to remove substantially all of thematerial remaining after contact of said wheel and said sheet.

13. A recorder adapted to be operated by picture signals comprisingmeans to hold and advance a record sheet, a transfer member presenting athin edge to said sheet, means to cause said member to scan said sheet,means to form a pattern of marking material on said edge in accordancewith received signals and means to cause said pattern to be transferredfrom said edge to said sheet.

14. A recorder adapted to be operated by picture signals comprisingmeans to hold and advance a record sheet, a transfer member presenting athin edge to said sheet, means comprising a moving filament carrying apigment and a signal controlled member for moving said filament into andout of contact with said edge to form a pattern of marking material onsaid edge in accordance with received signals, and

means to cause said pattern to be transferred from said edge to saidsheet.

15. In a facsimile recorder the combination of a scanner including arotatable transfer wheel and means movably to support a record receivingsurface in contact with said transfer wheel, means to cause said wheelto scan said record receiving surface and inking means to supply ink tosaid transfer wheel in accordance with sig; nals for transfer to saidrecording surface.

16. The combination of scanning means including a rotatable spiralmember and a cooperating printer member arranged to be moved radiallywith respect to said spiral member, carbon bearing means supportedbetween ysaid printer member and said spiral member to apply markingmaterial to the latter upon,radial movement of the printer member andmeans to support and move a record receiving sheet in continuous contactwith said spiral member, said last named means being spaced from saidprinter member.

17. The combination of scanning means including a rotatable spiralmember and a cooperating printer member arranged to be movedsubstantially radially with respect to said spiral member, an inkcarrying strip interposed between said printer member and said spiralmembeer to apply marking material to the latter upon radial movement ofthe printer member, and means arranged to support and move a recordreceiving sheet in continuous contact with said spiral member at a pointspaced circumferentially from said printer member.

18. In a facsimile recorder, a helical marking member, a paper strip onwhich recording is to be effected, means to apply tension to said stripto advance the same, a pivotally mounted elongated pressure memberdisposed substantially parallel to the axis of said marking member,means to cause said pressure member to bear against said marking memberwith substantially uniform pressure throughout its length, said stripbeing looped to pass over said pressure member between said pressuremember and said marking member, and guide means over which both runs ofsaid loop are drawn by said tension means, said guide member lyingsubstantially in a plane defined by the portion of said pressure memberwhich presses said strip against said marking member and the pivotalmounting axis of said pressure member, whereby the uniformity of contactof said strip with said marking member is independent of the tension insaid strip.

RALEIGH J. WISE.

